Effect of nonstoichiometry on elastic properties of niobium carbide NbCy

The investigation of structure of coarse-crystalline powders of nonstoichiometric niobium carbide NbCy have shown that the particles of these powders are monocrystalline and possesses anisotropy of elastic properties. The changes of elastic constants c(ij) in the homogeneity interval from NbC0.70 to NbC1.00 of nonstoichiometric niobium carbide are evaluated for the first time. It is found that the elastic stiffness constants cij of a disordered NbCy decrease as the niobium carbide composition deviates from stoichiometry. The lowest and almost independent of the direction (hkl) values of Ghkl for NbCy are observed in the (111) plane. The isotropic bulk, shear and Young's moduli of nonstoichiometric NbCy niobium carbide which are derived from its elastic constants cij corresponds to the generalized experimental literature data. It is established that the deviation of niobium carbide composition from stoichiometry is accompanied by decrease of the elastic anisotropy.

Automated summary

The investigation of coarse-crystalline powders of nonstoichiometric niobium carbide NbCy reveals that the particles are monocrystalline and possess anisotropy of elastic properties. The study evaluates the changes of elastic constants c(ij) in the homogeneity interval of nonstoichiometric niobium carbide from NbC0.70 to NbC1.00 for the first time. It is found that the elastic stiffness constants cij decrease as the composition of disordered NbCy deviates from stoichiometry, leading to a reduction in elastic anisotropy.